screensaver

[mike finnegan]

i'm having a problem with a screensaver i made...it works fine except for
the problem that when it loads, after a little while, additional instances
of the screensaver appear. There is an api call to get around this problem...i
just don't know what it is.
if any one knows it or can provide me a link to it, i'd appriciate it.

regards,
mike finnegan
(r8458@together.net)

[RDJ]

"mike finnegan" <r8458@together.net> wrote:
>
>i'm having a problem with a screensaver i made...it works fine except for
>the problem that when it loads, after a little while, additional instances
>of the screensaver appear. There is an api call to get around this problem...i
>just don't know what it is.
>if any one knows it or can provide me a link to it, i'd appriciate it.
>
>regards,
>mike finnegan
>(r8458@together.net)

T> r> y> [Search] single instance

or

Q & A - Ensuring Single Instance


Applies to These Versions Categories
Version Numbers Not Applicable Development and Programming Techniques


--------------------------------------------------------------------------------
I have a requirement to only allow a copy of an application to be executed
once. If someone tries to execute the app a second time, I want to give a
message saying "you're not allowed do this - you only paid for one execution".
Do you know a relatively surefire way of doing this? I can think of a few
partially acceptable ways but I want a really good method. The app in question
runs under Windows 3.x, uses an Access 2.0 database and the standard VB setup
program to install itself.

This routine takes advantage of a unique "feature" of Visual Basic applications:
the hidden parent. Every VB application has a parent window that remains
hidden. The caption on this parent window is the name of the application
as provided during the "Make EXE File" process. This is why the name of the
application, and not the main window's caption, appears in the Task List
when a user presses Ctrl-ESC. Since the parent window is hidden, there has
never been a need to change the caption in it. As a result, nearly all VB
programs can use this routine. In contrast, the only VB programs that could
use the previous routine were those that did not change the caption in their
own main window. This limitation may actually have contributed to programmers
choosing NOT to use the caption of their main window to impart information,
which is unacceptable. There is a class of programs that cannot use this
routine: those that set their Application Name in the "Make EXE file" dialog
to a zero-length string. Since a large number of windows have a caption of
no characters, setting your window title to no text prevents this routine
from finding your other instance. Be aware of one limitation in the code:
This routine uses App.Previnstance to detect if there is another instance
of the program to look for. This is done simply to improve performance, but
it has a price. App.Previnstance is set only when the application starts
up. Therefore, if you start two instances of the same app, the first one
will get a False value, while the second one will get a True value. Therefore,
the first instance cannot use this routine to detect the second. If you want
to use this routine to allow multiple instances to run, and to have both
routines aware of the other's window handle, then take out the use of App.Previnstance
completely. Also note that this routine will break down if you want to start
three or more instances of your application. If you need to do that, use
DDE to communicate between the instances. To declare the routines needed
by Get_Other_Instance, place the following lines in the declarations section
of the module or form where you put Get_Other_Instance:

Declare Function GetWindowWord% Lib "User" (ByVal hWnd%, ByVal nIndex%)
Declare Function GetWindowText% Lib "User" (ByVal hWnd%, ByVal lpString$,
ByVal aint%)
Declare Function GetWindowTextLength% Lib "User" (ByVal hWnd%)
Declare Function GetWindow% Lib "User" (ByVal hWnd%, ByVal wCmd%)
Declare Function SetFocusAPI% Lib "User" Alias "SetFocus" (ByVal hWnd%)

' get window word constants
Const GWW_HWNDPARENT = (-8)

' get window constants
Const GW_HWNDFIRST = 0
Const GW_HWNDNEXT = 2
To use the Get_Other_Instance routine, place the following lines in your
Form_Load routine:
Sub Form_Load()
Dim otherhwnd%

If Get_Other_Instance(Hwnd, otherhwnd%) then
MsgBox "Application is already running. Switching to existing Application"
SetFocusAPI otherhwnd%
End
End If

End Sub
The full text of Get_Other_Instance follows.
' ------------------------------------------------------------------------------------
' ROUTINE: Get_Other_Instance:BOOL, Params( inhwnd Inputonly, outhwnd
Outputonly)
' Purpose: to obtain the window handle of another instance of the same program
'
' Description: Unlike other examples, this one works even if the main window
changes
' the caption to reflect the loading of a data file (like MS WORD does).
This works by
' using a peculiarity of VB. Every VB program has a parent window above
the main window.
' The caption of the parent window is the text used in the "Make EXE" Dialog
for Application
' name. The VB programmer cannot easily change this text, and it is hidden
to the user,
' so it is good for this type of operation.
'
' INPUT: inhwnd -- the window handle of the calling window
' OUTPUT: return code is True if a window was found, FALSE otherwise
' outhwnd -- 0 or set to the hwnd of the parent of the other window
'
' ------------------------------------------------------------------------------------
'
Function get_other_instance (ByVal inhwnd As Integer, outhwnd As Integer)
As Integer
Dim parent%, nlen%, ptext$, nexthwnd%, wtext$
get_other_instance = False
outhwnd = 0
If Not app.PrevInstance Then Exit Function

parent% = GetWindowWord(inhwnd, GWW_HWNDPARENT)
nlen% = GetWindowTextLength(parent%) + 2
ptext$ = Space$(nlen%)
nlen% = GetWindowText(parent%, ptext$, nlen%)
ptext$ = Left$(ptext$, nlen%)
nexthwnd% = GetWindow(parent%, GW_HWNDFIRST) ' get the first window in
the window list
Do While nexthwnd% > 0
nlen% = GetWindowTextLength(nexthwnd%) + 2
wtext$ = Space$(nlen%)
nlen% = GetWindowText(nexthwnd%, wtext$, nlen%)
wtext$ = Left$(wtext$, nlen%)
If wtext$ = ptext$ And nexthwnd% <> parent% Then
get_other_instance = True
outhwnd = nexthwnd%
Exit Do
End If
nexthwnd% = GetWindow(nexthwnd%, GW_HWNDNEXT)
Loop

End Function

Written by Eric Smith on 10/1/96.

[RDJ]

"mike finnegan" <r8458@together.net> wrote:
>
>i'm having a problem with a screensaver i made...it works fine except for
>the problem that when it loads, after a little while, additional instances
>of the screensaver appear. There is an api call to get around this problem...i
>just don't know what it is.
>if any one knows it or can provide me a link to it, i'd appriciate it.
>
>regards,
>mike finnegan
>(r8458@together.net)

T> r> y> [Search] single instance

or

Q & A - Ensuring Single Instance


Applies to These Versions Categories
Version Numbers Not Applicable Development and Programming Techniques


--------------------------------------------------------------------------------
I have a requirement to only allow a copy of an application to be executed
once. If someone tries to execute the app a second time, I want to give a
message saying "you're not allowed do this - you only paid for one execution".
Do you know a relatively surefire way of doing this? I can think of a few
partially acceptable ways but I want a really good method. The app in question
runs under Windows 3.x, uses an Access 2.0 database and the standard VB setup
program to install itself.

This routine takes advantage of a unique "feature" of Visual Basic applications:
the hidden parent. Every VB application has a parent window that remains
hidden. The caption on this parent window is the name of the application
as provided during the "Make EXE File" process. This is why the name of the
application, and not the main window's caption, appears in the Task List
when a user presses Ctrl-ESC. Since the parent window is hidden, there has
never been a need to change the caption in it. As a result, nearly all VB
programs can use this routine. In contrast, the only VB programs that could
use the previous routine were those that did not change the caption in their
own main window. This limitation may actually have contributed to programmers
choosing NOT to use the caption of their main window to impart information,
which is unacceptable. There is a class of programs that cannot use this
routine: those that set their Application Name in the "Make EXE file" dialog
to a zero-length string. Since a large number of windows have a caption of
no characters, setting your window title to no text prevents this routine
from finding your other instance. Be aware of one limitation in the code:
This routine uses App.Previnstance to detect if there is another instance
of the program to look for. This is done simply to improve performance, but
it has a price. App.Previnstance is set only when the application starts
up. Therefore, if you start two instances of the same app, the first one
will get a False value, while the second one will get a True value. Therefore,
the first instance cannot use this routine to detect the second. If you want
to use this routine to allow multiple instances to run, and to have both
routines aware of the other's window handle, then take out the use of App.Previnstance
completely. Also note that this routine will break down if you want to start
three or more instances of your application. If you need to do that, use
DDE to communicate between the instances. To declare the routines needed
by Get_Other_Instance, place the following lines in the declarations section
of the module or form where you put Get_Other_Instance:

Declare Function GetWindowWord% Lib "User" (ByVal hWnd%, ByVal nIndex%)
Declare Function GetWindowText% Lib "User" (ByVal hWnd%, ByVal lpString$,
ByVal aint%)
Declare Function GetWindowTextLength% Lib "User" (ByVal hWnd%)
Declare Function GetWindow% Lib "User" (ByVal hWnd%, ByVal wCmd%)
Declare Function SetFocusAPI% Lib "User" Alias "SetFocus" (ByVal hWnd%)

' get window word constants
Const GWW_HWNDPARENT = (-8)

' get window constants
Const GW_HWNDFIRST = 0
Const GW_HWNDNEXT = 2
To use the Get_Other_Instance routine, place the following lines in your
Form_Load routine:
Sub Form_Load()
Dim otherhwnd%

If Get_Other_Instance(Hwnd, otherhwnd%) then
MsgBox "Application is already running. Switching to existing Application"
SetFocusAPI otherhwnd%
End
End If

End Sub
The full text of Get_Other_Instance follows.
' ------------------------------------------------------------------------------------
' ROUTINE: Get_Other_Instance:BOOL, Params( inhwnd Inputonly, outhwnd
Outputonly)
' Purpose: to obtain the window handle of another instance of the same program
'
' Description: Unlike other examples, this one works even if the main window
changes
' the caption to reflect the loading of a data file (like MS WORD does).
This works by
' using a peculiarity of VB. Every VB program has a parent window above
the main window.
' The caption of the parent window is the text used in the "Make EXE" Dialog
for Application
' name. The VB programmer cannot easily change this text, and it is hidden
to the user,
' so it is good for this type of operation.
'
' INPUT: inhwnd -- the window handle of the calling window
' OUTPUT: return code is True if a window was found, FALSE otherwise
' outhwnd -- 0 or set to the hwnd of the parent of the other window
'
' ------------------------------------------------------------------------------------
'
Function get_other_instance (ByVal inhwnd As Integer, outhwnd As Integer)
As Integer
Dim parent%, nlen%, ptext$, nexthwnd%, wtext$
get_other_instance = False
outhwnd = 0
If Not app.PrevInstance Then Exit Function

parent% = GetWindowWord(inhwnd, GWW_HWNDPARENT)
nlen% = GetWindowTextLength(parent%) + 2
ptext$ = Space$(nlen%)
nlen% = GetWindowText(parent%, ptext$, nlen%)
ptext$ = Left$(ptext$, nlen%)
nexthwnd% = GetWindow(parent%, GW_HWNDFIRST) ' get the first window in
the window list
Do While nexthwnd% > 0
nlen% = GetWindowTextLength(nexthwnd%) + 2
wtext$ = Space$(nlen%)
nlen% = GetWindowText(nexthwnd%, wtext$, nlen%)
wtext$ = Left$(wtext$, nlen%)
If wtext$ = ptext$ And nexthwnd% <> parent% Then
get_other_instance = True
outhwnd = nexthwnd%
Exit Do
End If
nexthwnd% = GetWindow(nexthwnd%, GW_HWNDNEXT)
Loop

End Function

Written by Eric Smith on 10/1/96.

[Rishi Dhruv]

"RDJ" <rjong@step-stone.com> wrote:
>
>"mike finnegan" <r8458@together.net> wrote:
>>
>>i'm having a problem with a screensaver i made...it works fine except for
>>the problem that when it loads, after a little while, additional instances
>>of the screensaver appear. There is an api call to get around this problem...i
>>just don't know what it is.
>>if any one knows it or can provide me a link to it, i'd appriciate it.
>>
>>regards,
>>mike finnegan
>>(r8458@together.net)
>
>T> r> y> [Search] single instance
>
>or
>
> Q & A - Ensuring Single Instance
>
>
>Applies to These Versions Categories
>Version Numbers Not Applicable Development and Programming Techniques
>
>
>--------------------------------------------------------------------------------
>I have a requirement to only allow a copy of an application to be executed
>once. If someone tries to execute the app a second time, I want to give
a
>message saying "you're not allowed do this - you only paid for one execution".
>Do you know a relatively surefire way of doing this? I can think of a few
>partially acceptable ways but I want a really good method. The app in question
>runs under Windows 3.x, uses an Access 2.0 database and the standard VB
setup
>program to install itself.
>
>This routine takes advantage of a unique "feature" of Visual Basic applications:
>the hidden parent. Every VB application has a parent window that remains
>hidden. The caption on this parent window is the name of the application
>as provided during the "Make EXE File" process. This is why the name of
the
>application, and not the main window's caption, appears in the Task List
>when a user presses Ctrl-ESC. Since the parent window is hidden, there has
>never been a need to change the caption in it. As a result, nearly all VB
>programs can use this routine. In contrast, the only VB programs that could
>use the previous routine were those that did not change the caption in their
>own main window. This limitation may actually have contributed to programmers
>choosing NOT to use the caption of their main window to impart information,
>which is unacceptable. There is a class of programs that cannot use this
>routine: those that set their Application Name in the "Make EXE file" dialog
>to a zero-length string. Since a large number of windows have a caption
of
>no characters, setting your window title to no text prevents this routine
>from finding your other instance. Be aware of one limitation in the code:
>This routine uses App.Previnstance to detect if there is another instance
>of the program to look for. This is done simply to improve performance,
but
>it has a price. App.Previnstance is set only when the application starts
>up. Therefore, if you start two instances of the same app, the first one
>will get a False value, while the second one will get a True value. Therefore,
>the first instance cannot use this routine to detect the second. If you
want
>to use this routine to allow multiple instances to run, and to have both
>routines aware of the other's window handle, then take out the use of App.Previnstance
>completely. Also note that this routine will break down if you want to start
>three or more instances of your application. If you need to do that, use
>DDE to communicate between the instances. To declare the routines needed
>by Get_Other_Instance, place the following lines in the declarations section
>of the module or form where you put Get_Other_Instance:
>
>Declare Function GetWindowWord% Lib "User" (ByVal hWnd%, ByVal nIndex%)
>Declare Function GetWindowText% Lib "User" (ByVal hWnd%, ByVal lpString$,
>ByVal aint%)
>Declare Function GetWindowTextLength% Lib "User" (ByVal hWnd%)
>Declare Function GetWindow% Lib "User" (ByVal hWnd%, ByVal wCmd%)
>Declare Function SetFocusAPI% Lib "User" Alias "SetFocus" (ByVal hWnd%)
>
>' get window word constants
> Const GWW_HWNDPARENT = (-8)
>
>' get window constants
> Const GW_HWNDFIRST = 0
> Const GW_HWNDNEXT = 2
>To use the Get_Other_Instance routine, place the following lines in your
>Form_Load routine:
>Sub Form_Load()
> Dim otherhwnd%
>
> If Get_Other_Instance(Hwnd, otherhwnd%) then
> MsgBox "Application is already running. Switching to existing Application"
> SetFocusAPI otherhwnd%
> End
> End If
>
>End Sub
>The full text of Get_Other_Instance follows.
>' ------------------------------------------------------------------------------------
>' ROUTINE: Get_Other_Instance:BOOL, Params( inhwnd Inputonly, outhwnd
>Outputonly)
>' Purpose: to obtain the window handle of another instance of the same
program
>'
>' Description: Unlike other examples, this one works even if the main window
>changes
>' the caption to reflect the loading of a data file (like MS WORD does).
> This works by
>' using a peculiarity of VB. Every VB program has a parent window above
>the main window.
>' The caption of the parent window is the text used in the "Make EXE" Dialog
>for Application
>' name. The VB programmer cannot easily change this text, and it is hidden
>to the user,
>' so it is good for this type of operation.
>'
>' INPUT: inhwnd -- the window handle of the calling window
>' OUTPUT: return code is True if a window was found, FALSE otherwise
>' outhwnd -- 0 or set to the hwnd of the parent of the other window
>'
>' ------------------------------------------------------------------------------------
>'
>Function get_other_instance (ByVal inhwnd As Integer, outhwnd As Integer)
>As Integer
> Dim parent%, nlen%, ptext$, nexthwnd%, wtext$
> get_other_instance = False
> outhwnd = 0
> If Not app.PrevInstance Then Exit Function
>
> parent% = GetWindowWord(inhwnd, GWW_HWNDPARENT)
> nlen% = GetWindowTextLength(parent%) + 2
> ptext$ = Space$(nlen%)
> nlen% = GetWindowText(parent%, ptext$, nlen%)
> ptext$ = Left$(ptext$, nlen%)
> nexthwnd% = GetWindow(parent%, GW_HWNDFIRST) ' get the first window
in
>the window list
> Do While nexthwnd% > 0
> nlen% = GetWindowTextLength(nexthwnd%) + 2
> wtext$ = Space$(nlen%)
> nlen% = GetWindowText(nexthwnd%, wtext$, nlen%)
> wtext$ = Left$(wtext$, nlen%)
> If wtext$ = ptext$ And nexthwnd% <> parent% Then
> get_other_instance = True
> outhwnd = nexthwnd%
> Exit Do
> End If
> nexthwnd% = GetWindow(nexthwnd%, GW_HWNDNEXT)
> Loop
>
>End Function
>
>Written by Eric Smith on 10/1/96.
>

Hi there,

To if u don't want anther instance of ur app. then just try this -
If App.PrevInstance = true then
MsgBox <Message>
End
End If
- in ur load or Init event.

Hope this helps U.
Good Luck !
Bye .......

[Rishi Dhruv]

"RDJ" <rjong@step-stone.com> wrote:
>
>"mike finnegan" <r8458@together.net> wrote:
>>
>>i'm having a problem with a screensaver i made...it works fine except for
>>the problem that when it loads, after a little while, additional instances
>>of the screensaver appear. There is an api call to get around this problem...i
>>just don't know what it is.
>>if any one knows it or can provide me a link to it, i'd appriciate it.
>>
>>regards,
>>mike finnegan
>>(r8458@together.net)
>
>T> r> y> [Search] single instance
>
>or
>
> Q & A - Ensuring Single Instance
>
>
>Applies to These Versions Categories
>Version Numbers Not Applicable Development and Programming Techniques
>
>
>--------------------------------------------------------------------------------
>I have a requirement to only allow a copy of an application to be executed
>once. If someone tries to execute the app a second time, I want to give
a
>message saying "you're not allowed do this - you only paid for one execution".
>Do you know a relatively surefire way of doing this? I can think of a few
>partially acceptable ways but I want a really good method. The app in question
>runs under Windows 3.x, uses an Access 2.0 database and the standard VB
setup
>program to install itself.
>
>This routine takes advantage of a unique "feature" of Visual Basic applications:
>the hidden parent. Every VB application has a parent window that remains
>hidden. The caption on this parent window is the name of the application
>as provided during the "Make EXE File" process. This is why the name of
the
>application, and not the main window's caption, appears in the Task List
>when a user presses Ctrl-ESC. Since the parent window is hidden, there has
>never been a need to change the caption in it. As a result, nearly all VB
>programs can use this routine. In contrast, the only VB programs that could
>use the previous routine were those that did not change the caption in their
>own main window. This limitation may actually have contributed to programmers
>choosing NOT to use the caption of their main window to impart information,
>which is unacceptable. There is a class of programs that cannot use this
>routine: those that set their Application Name in the "Make EXE file" dialog
>to a zero-length string. Since a large number of windows have a caption
of
>no characters, setting your window title to no text prevents this routine
>from finding your other instance. Be aware of one limitation in the code:
>This routine uses App.Previnstance to detect if there is another instance
>of the program to look for. This is done simply to improve performance,
but
>it has a price. App.Previnstance is set only when the application starts
>up. Therefore, if you start two instances of the same app, the first one
>will get a False value, while the second one will get a True value. Therefore,
>the first instance cannot use this routine to detect the second. If you
want
>to use this routine to allow multiple instances to run, and to have both
>routines aware of the other's window handle, then take out the use of App.Previnstance
>completely. Also note that this routine will break down if you want to start
>three or more instances of your application. If you need to do that, use
>DDE to communicate between the instances. To declare the routines needed
>by Get_Other_Instance, place the following lines in the declarations section
>of the module or form where you put Get_Other_Instance:
>
>Declare Function GetWindowWord% Lib "User" (ByVal hWnd%, ByVal nIndex%)
>Declare Function GetWindowText% Lib "User" (ByVal hWnd%, ByVal lpString$,
>ByVal aint%)
>Declare Function GetWindowTextLength% Lib "User" (ByVal hWnd%)
>Declare Function GetWindow% Lib "User" (ByVal hWnd%, ByVal wCmd%)
>Declare Function SetFocusAPI% Lib "User" Alias "SetFocus" (ByVal hWnd%)
>
>' get window word constants
> Const GWW_HWNDPARENT = (-8)
>
>' get window constants
> Const GW_HWNDFIRST = 0
> Const GW_HWNDNEXT = 2
>To use the Get_Other_Instance routine, place the following lines in your
>Form_Load routine:
>Sub Form_Load()
> Dim otherhwnd%
>
> If Get_Other_Instance(Hwnd, otherhwnd%) then
> MsgBox "Application is already running. Switching to existing Application"
> SetFocusAPI otherhwnd%
> End
> End If
>
>End Sub
>The full text of Get_Other_Instance follows.
>' ------------------------------------------------------------------------------------
>' ROUTINE: Get_Other_Instance:BOOL, Params( inhwnd Inputonly, outhwnd
>Outputonly)
>' Purpose: to obtain the window handle of another instance of the same
program
>'
>' Description: Unlike other examples, this one works even if the main window
>changes
>' the caption to reflect the loading of a data file (like MS WORD does).
> This works by
>' using a peculiarity of VB. Every VB program has a parent window above
>the main window.
>' The caption of the parent window is the text used in the "Make EXE" Dialog
>for Application
>' name. The VB programmer cannot easily change this text, and it is hidden
>to the user,
>' so it is good for this type of operation.
>'
>' INPUT: inhwnd -- the window handle of the calling window
>' OUTPUT: return code is True if a window was found, FALSE otherwise
>' outhwnd -- 0 or set to the hwnd of the parent of the other window
>'
>' ------------------------------------------------------------------------------------
>'
>Function get_other_instance (ByVal inhwnd As Integer, outhwnd As Integer)
>As Integer
> Dim parent%, nlen%, ptext$, nexthwnd%, wtext$
> get_other_instance = False
> outhwnd = 0
> If Not app.PrevInstance Then Exit Function
>
> parent% = GetWindowWord(inhwnd, GWW_HWNDPARENT)
> nlen% = GetWindowTextLength(parent%) + 2
> ptext$ = Space$(nlen%)
> nlen% = GetWindowText(parent%, ptext$, nlen%)
> ptext$ = Left$(ptext$, nlen%)
> nexthwnd% = GetWindow(parent%, GW_HWNDFIRST) ' get the first window
in
>the window list
> Do While nexthwnd% > 0
> nlen% = GetWindowTextLength(nexthwnd%) + 2
> wtext$ = Space$(nlen%)
> nlen% = GetWindowText(nexthwnd%, wtext$, nlen%)
> wtext$ = Left$(wtext$, nlen%)
> If wtext$ = ptext$ And nexthwnd% <> parent% Then
> get_other_instance = True
> outhwnd = nexthwnd%
> Exit Do
> End If
> nexthwnd% = GetWindow(nexthwnd%, GW_HWNDNEXT)
> Loop
>
>End Function
>
>Written by Eric Smith on 10/1/96.
>

Hi there,

To if u don't want anther instance of ur app. then just try this -
If App.PrevInstance = true then
MsgBox <Message>
End
End If
- in ur load or Init event.

Hope this helps U.
Good Luck !
Bye .......

[Don Bradner]

"mike finnegan" <r8458@together.net> wrote:

>i'm having a problem with a screensaver i made...it works fine except for
>the problem that when it loads, after a little while, additional instances
>of the screensaver appear. There is an api call to get around this problem...i
>just don't know what it is.
>if any one knows it or can provide me a link to it, i'd appriciate it.

There is the general issue of checking for a previous instance, mentioned in
another answer, and there is also the specific issue of stopping the system
from trying to start another screen saver instance. You can do the latter by
using SystemParametersInfo with SPI_SCREENSAVERRUNNING.

"Good" screen saver techniques generally include the SPI call only when
passwords are enabled, because it also stops Ctrl-Alt-Del. So, a combination
of practices works best. The screen saver example that Jim Deutch and I wrote
uses both techniques, and can be found at www.arcatapet.com/vb.html.
Don Bradner
don@arcatapet.com
www.arcatapet.com

[Don Bradner]

"mike finnegan" <r8458@together.net> wrote:

>i'm having a problem with a screensaver i made...it works fine except for
>the problem that when it loads, after a little while, additional instances
>of the screensaver appear. There is an api call to get around this problem...i
>just don't know what it is.
>if any one knows it or can provide me a link to it, i'd appriciate it.

There is the general issue of checking for a previous instance, mentioned in
another answer, and there is also the specific issue of stopping the system
from trying to start another screen saver instance. You can do the latter by
using SystemParametersInfo with SPI_SCREENSAVERRUNNING.

"Good" screen saver techniques generally include the SPI call only when
passwords are enabled, because it also stops Ctrl-Alt-Del. So, a combination
of practices works best. The screen saver example that Jim Deutch and I wrote
uses both techniques, and can be found at www.arcatapet.com/vb.html.
Don Bradner
don@arcatapet.com
www.arcatapet.com